ETSI TR 102 799 V1.1.1 (2010-06)

Electromagnetic compatibility and Radio spectrum Matters (ERM); Operation methods and principles for spectrum access systems for PMSE technologies and the guarantee of a high sound production quality on selected frequencies utilising cognitive interference mitigation techniques

DTR/ERM-TG17WG3-011

General Information

• Status: Published
• Publication Date: 13-Jun-2010
• Technical Committee: ERM TG17 WG3 - ERM Radio Microphones, Cordless Audio and Audio Links
• Current Stage: 12 - Completion
• Due Date: 23-Jun-2010
• Completion Date: 14-Jun-2010

Standards Content (Sample)

Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Operation methods and principles for spectrum access
systems for PMSE technologies and the guarantee of a high
sound production quality on selected frequencies utilising
cognitive interference mitigation techniques

2 ETSI TR 102 799 V1.1.1 (2010-06)

Reference
DTR/ERM-TG17WG3-011
Keywords
access, radio
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3 ETSI TR 102 799 V1.1.1 (2010-06)
Contents
Intellectual Property Rights . 6
Foreword . 6
Introduction . 6
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 11
4 Differences between mobile services and Professional Audio Transmission . 12
4.1 General remarks . 12
4.2 Comparisons in the operation of PSME against other mobile systems . 13
4.3 Latency . 13
4.4 Signalling between mobile and infrastructure equipment . 13
4.5 Link reliability . 13
4.6 Link quality . 14
4.7 Link Robustness . 15
4.8 Radio Resource Management (RRM) . 15
4.9 Source Coding and Audio/Speech Compression . 15
4.10 Spectral Efficiency . 16
4.10.1 PMSE Calculation . 16
4.10.2 Example . 16
4.11 Mobility . 16
4.12 Interference Scenarios . 16
4.13 Training and Channel Sounding . 17
4.14 Encryption . 17
4.15 Coverage area . 17
4.16 Power Consumption on Mobile Device. 17
4.17 Characteristics of Wi-Fi versus PMSE and other mobile systems . 17
5 Frequency Bands in consideration . 18
5.1 Overview . 18
5.1.1 Narrow audio: 29,7 MHz to 47 MHz . 18
5.1.2 VHF: 174 MHz to 216 MHz . 18
5.1.3 UHF: 470 MHz to 862 MHz . 18
5.1.4 Duplex Guard band: 821 MHz to 832 MHz . 19
5.1.5 863 MHz to 865 MHz . 19
5.1.6 L-Band . 19
5.1.6.1 L-Band part 1: 1 452 MHz to 1 477 MHz (1 479,5 MHz) . 19
5.1.6.2 L-Band part 2: 1 492 MHz to 1 518 MHz . 19
5.1.6.3 L-Band part 3: 1 518 MHz to 1 559 MHz . 19
5.1.7 1,8 GHz: 1 785 MHz to 1 800 MHz . 19
5.1.8 ISM-band: 2,4 GHz and 5,8 GHz . 19
5.2 Technical characteristics of specific frequency bands . 20
6. Cognitive Technologies . 20
6.1 Definition of Cognitive Communication System . 20
6.2 Functional Architecture of a Cognitive Radio . 22
6.3 Cognitive Technologies . 23
6.3.1 Technologies for making observations . 23
6.3.1.1 Spectrum Sensing and Classification . 23
6.3.1.1.1 Energy Detection . 23
6.3.1.1.2 Feature Detection. 24
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6.3.1.1.3 Limitations and Challenges . 24
6.3.1.2 Radio Environment Map . 26
6.3.1.3 Localization . 27
6.3.1.3.1 Expected performance of indoor geolocation technologies . 27
6.3.1.4 Cognitive Pilot Channel . 28
6.3.1.4.1 Information transmitted in the CPC . 28
6.3.1.4.2 Operation modes . 28
6.3.1.4.3 Delivery modes . 28
6.3.1.4.4 Benefits of CPC . 29
6.3.1.4.5 Drawbacks of CPC . 29
6.3.2 Technologies for making Actions: Radio Resource Management (RRM) . 29
6.3.2.1 Dynamic Frequency Allocation (DFA) . 29
6.3.2.2 Bandwidth Scalability . 30
6.3.2.3 Dynamic Power Control (DPC) . 30
6.3.2.4 Pre-emption - Priority Management . 30
7 Cognitive PMSE System (C-PMSE System) . 30
7.1 Definition C-PMSE . 30
7.1.1 Observe . 32
7.1.2 Understand . 32
7.1.3 Predict . 32
7.1.4 Decide . 32
7.1.5 Act . 33
7.2 C-PMSE System Architecture . 33
7.3 Description of Functional Elements . 34
7.3.1 Radio Resource Manager (RRM) . 34
7.3.2 Service Level Entry (SLE) . 35
7.3.3 Service Level Monitor (SLM) . 35
7.3.4 Cognitive Engine (CEN) . 35
7.3.5 Performance Monitor (PMO) . 35
7.3.6 Scanning Receiver (SCR) . 36
7.3.7 Frequency Coordinator (FCO) . 36
7.4 Interfaces/Protocols . 36
7.4.1 Frequency Coordination Interface (fci) . 37
7.4.1.1 Information provided from FCO . 37
7.4.1.2 Information provided to the FCO . 37
7.4.1.3 Other organizational aspects / open issues . 37
7.4.2 Inter cognitive PMSE Interface (cpi) . 37
7.4.3 Scanning Receiver Interface (sci) . 37
8 C-PMSE Scenarios and Use Cases . 38
8.1 Introduction . 38
8.2 Usage Scenarios . 39
8.2.1 The static scenario . 39
8.2.1.1 The state of the art use case . 39
8.2.1.2 The extended use case . 41
8.2.2 The dynamic scenario . 43
9 Hierarchical Database for Spectrum Management . 47
9.1 The Current State of the Art . 48
9.2 Structure and Architecture Proposal . 48
9.3 Database Security and Access Methods . 49
9.4 Database Update and Spectrum Lease . 49
9.5 Database Legacy Support . 49
9.6 Database Content . 49
9.7 Location Accuracy Parameter . 50
10 RF parameters of PMSE Audio services and quality service levels . 51
11 Conclusions and Recommendations . 51
11.1 Hidden Node Problem / "Ask Before Talk" . 51
11.2 Intermodulation . 51
11.3 Interference Power . 52
11.4 Compatibility of cognitive devices in the 470 MHz to 862 MHz band . 52
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5 ETSI TR 102 799 V1.1.1 (2010-06)
11.5 Interference by CDs. 52
11.6 Propagation and Interference characteristics . 52
11.7 QoS Monitoring . 52
11.8 Spectral efficiency . 52
11.9 Radio Resource Management . 53
11.10 Hierarchical Database . 53
11.11 Geolocation accuracy . 53
11.12 Database security . 53
Annex A: Bibliography . 54
History . 55

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6 ETSI TR 102 799 V1.1.1 (2010-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
A future ETSI Technical Specification on the recommended spectrum access technique in the present document is
planned as well as tests on a demonstrator built to the specifications in the TS. An ETSI Technical Report on the
defined RF compliance tests carried out on the demonstrator for the selected spectrum access mechanism defined in the
TS is planned to be prepared.
Please note that although the technology demonstrator will concentrate on one particular application, the technology
will ultimately be transferable to other PMSE applications.
Introduction
Radio microphone devices use 100 % duty cycle to convey voice or music either for a live event such as concerts and
theatres or for a recorded event such as the production of film and television programs. Interference during this process
is not only commercially disastrous; it can be also harmful to the audience where a public address system is in use.
The regulations governing the operation of PMSE (Program Making and Special Events) systems are currently in flux
in Europe. During the process of changeover compression of the television channels is taking place below 790 MHz.
The spectrum between 790 MHz and 862 MHz has been considered a Digital Dividend and allocated for use by
Electronic Communications Networks. This has resulted in a reduction of spectrum available for PSME.
Protection
PMSE devices use very low radiated power levels (the maximum PWMS RF power level is 50 mW) in comparison to
most other radio communication systems. In order for them to function properly, they are protected from interference.
Up to now this has not been a problem since PMSE equipment operated in locally unused TV channels that presented a
very predictable RF environment. In the future, many different kinds of new devices, the characteristics of which are
difficult to fully anticipate at this time, may be sharing this space. Some of these devices will be used for broadband
data, and will occupy any spectrum which is available to them, i.e. from a few MHz to a multiple of 10 MHz. Other
uses of the Digital Dividend, which may eventually go down to 600 MHz, are use by the emergency services and other
mobile services.
The question of how to protect PMSE equipment from interference caused by new devices has been the subject of much
discussion and debate. Traditionally, incompatible radio communications systems were assigned to operate in separate
frequency bands, but this scheme is becoming impractical in today's world of intensive spectrum use. A more dynamic
and robust solution is needed.
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7 ETSI TR 102 799 V1.1.1 (2010-06)
Spectrum efficiency
Including cognitive techniques into a PMSE system has a high potential for increasing spectrum efficiency. It has to be
investigated which cognitive techniques are suitable and how they need to be modified to serve the needs of the PMSE
system.
Flexibility of spectrum access
Including cognitive techniques into a PMSE system has a high potential for increasing the flexibility of spectrum
access. It has to be investigated which cognitive techniques are suitable and how they need to be modified to serve the
PMSE systems needs.
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8 ETSI TR 102 799 V1.1.1 (2010-06)
1 Scope
The present document analyses the various possible techniques for spectrum access systems for PMSE technologies and
for the guarantee of a high sound production quality on selected frequencies utilising cognitive interference mitigation
techniques and recommends a specific method.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TR 102 683 (V1.1.1): "Reconfigurable Radio Systems (RRS); Cognitive Pilot Channel
(CPC)".
[i.2] Li, Y., Quang, T. T., Kawahara, Y., Asami, T., and Kusunoki, M. 2009. Building a spectrum map
for future cognitive radio technology. In Proceedings of the 2009 ACM Workshop on Cognitive
Radio Networks (Beijing, China, September 21 - 21, 2009). CoRoNet '09. ACM, New York,
NY, 1-6.
[i.3] WiMAX Forum Spectrum and Regulatory Database.
NOTE: http://www.wimaxforum.org/resources/wimax-forum-spectrum-and-regulatory-database
[i.4] TEDDI database.
NOTE: http://webapp.etsi.org/Teddi/
[i.5] ETSI EN 300 422 (V1.3.2): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Wireless microphones in the 25 MHz to 3 GHz frequency range".
[i.6] ETSI TR 102 546 (V1.1.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM);
Technical characteristics for Professional Wireless Microphone Systems (PWMS); System
Reference Document".
[i.7] ERC Recommendation 70-03 (2009): "Relating to the use of Short Range Devices (SRD) PWMS:
Annex 10 + Annex 13".
[i.8] CEPT Report 30: "Technical identification of common and minimal (least restrictive) technical
conditions for 790 - 862 MHz for the digital dividend in the European Union".
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9 ETSI TR 102 799 V1.1.1 (2010-06)
[i.9] CEPT Report 32: "Recommendation on the best approach to ensure the continuation of existing
Program Making and Special Events (PMSE) services operating in the UHF (470-862 MHz),
including the assessment of the advantage of an EU-level approach".
[i.10] ETSI EN 300 726 (V7.0.2): "Digital cellular telecommunications system (Phase 2+) (GSM);
Enhanced Full Rate (EFR) speech transcoding (GSM 06.60 version 7.0.2 Release 1998)".
[i.11] Draft ECC Report 147: "Additional compatibility studies relating to PWMS in the band 1518-1559
MHz excluding the band 1544-1545 MHz".
[i.12] OET Report, FCC/OET 08-TR-1005: "Evaluation of the Performance of Prototype TV-Band
White Space Devices Phase II".
[i.13] ETSI TR 102 802: "Reconfigurable Radio Systems (RRS); Cognitive Radio System Concept".
3 Definitions and abbreviations
Further definitions can be found on Terms and Definitions Interactive Database (TEDDI) [i.4].
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Adaptive Modulation and Coding (AMC): protocol that sets modulation and coding parameters depending on
channel state
Ask Before Talk (ABT): spectrum access protocol requiring a cognitive radio device to consult a local database,
frequency coordinator or other authority before starting transmission
Cognitive PMSE system (C-PMSE): PMSE system, which includes a Cognitive Engine (CEN)
NOTE: See ITU definition CRS below. However adding the highlighted wording:
A radio system (optionally including multiple entities and network elements), which has the following capabilities:
- to obtain the knowledge of radio operational environment and established policies and to monitor usage
patterns and users' needs;
- to dynamically, autonomously and whenever possible proactively adjust its operational parameters and
protocols according to this knowledge in order to achieve predefined objectives, e.g. minimize a loss in
performance or increase spectrum efficiency;
- and to learn from the results of its actions in order to further improve its performance
Cognitive Radio System (CRS): radio system (optionally including multiple entities and network elements), which has
the following capabilities:
• to obtain the knowledge of radio operational environment and established policies and to monitor usage
patterns and users' needs;
• to dynamically, autonomously and whenever possible adjust its operational parameters and protocols
according to this knowledge in order to achieve predefined objectives, e.g. minimize a loss in performance or
increase spectrum efficiency; and to learn from the results of its actions in order to further improve its
performance
content plane: contains audio and/or video information, analogue or digital
NOTE: The term data plane/data channel is not used in the present document due to potential irritations. Instead
signalling and content plane are used.
control plane: control data plane (contains control and management information)
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10 ETSI TR 102 799 V1.1.1 (2010-06)
Detect And Avoid (DAA): technology used to protect radio communication services by avoiding co-channel operation
NOTE: DAA operates as follows: before transmitting, a system senses the channel within its operative bandwidth
in order to detect the possible presence of other systems. If another system is detected, the first system
avoids the transmission until the detected system disappears.
Direct Mode: Mobile-to-Mobile communication
downlink: communication from master to slave
NOTE: The terms "Forward / Reverse Link" are not used in the present document due to potential irritations.
Instead downlink and uplink are used.
Dynamic Frequency Allocation (DFA): protocol that allows for changing transmit frequency during operation
Dynamic Power Control (DPC): capability that enables the transmitter output power of a device to be adjusted during
operation in accordance with its link budget requirements or other conditions
fixed: physically fixed, non- moving device
NOTE: includes temporary event installations as well.
infrastructure: nomadic entities
latency: time difference between input and output
NOTE: A professional audio system consists of many different devices such as loudspeakers, amplifiers, mixing
desks, etc . The PMSE latency value discussed in the present document is defined as analogue electric
audio input to analogue electric audio output from one transmitting device to its receiving device.
link adaptation: result of applying all of the control mechanisms used in Radio Resource Management to optimize the
performance of the radio link
Listen Before Talk (LBT): spectrum access protocol requiring a cognitive radio to perform spectrum sensing before
transmitting
location awareness: capability that allows a device to determine its location to a defined level of precision
master: unit which controls the radio resource changing actions
mobile: physically moving device
Professional Wireless Microphone System (PWMS): wireless microphones, IEM, audio links, etc.
Programme Making and Special Events (PMSE): production equipment, especially wireless equipment used by
broadcasters, musical and theatrical shows, and others
radio environment map: integrated multi-domain database that characterizes the radio environment in which a
cognitive radio system finds itself

NOTE: It may contain geographical information, available radio communication services, spectral regulations and
policies, and locations and activities of collocated radios.
Service Level Agreement (SLA): defined level of service agreed between the contractor and the service provider
signalling plane: plane which contains only signalling information, e.g. Radio Resource commands, battery status, etc.
NOTE: The term data plane / data channel is not used in the present document due to potential irritations. Instead
signalling and content plane are used.
slave: unit which performs the commanded actions by the Master
uplink: direction from Slave to Master
NOTE: The terms "Forward / Reverse Link" are not used in the present document due to potential irritations.
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white space: label indicating a part of the spectrum, which is available for a radio communication application (service,
system) at a given time in a given geographical area on a non-interfering / non-protected basis with regard to other
services with a higher priority on a national basis
White Space Device (WSD) = TV Band Device (TVBD): cognitive devices proposed to work in the
VHF / UHF-TV-Band
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ABT Ask Before Talk
AMC Adaptive Modulation and Coding
AMCT Adaptive Allocation Table
AMR Adaptive Modulation Rate
AP Access Point
BER Bit Error Rate
CEN Cognitive Engine
CPC Cognitive Pilot Channel
cpi inter cognitive PMSE interface
C-PMSE Cognitive - Programme Making Special Event entity or system
CRS Cognitive Radio System
CSI Channel State Information
DAA Detect And Avoid
DAT Device Allocation Table
DEM Device Manager
DFA Dynamic Frequency Allocation
DIC Diversity Interference Cancellation
DIP Dual In-line Package
DPC Dynamic Power Control
DTV Digital TeleVision
DVB-T Digital Video Broadcasting - Terrestrial
ECN Electronic Communications Network
EFR Enhance Full Rate
EIRP Equivalent Isotropic Radiated Power
ENG Electronic News Gathering
FAT Frequency Allocation Table
FCC Federal Communications Commission (U.S.)
fci frequency coordinator interface
FCO Frequency Coordinator
FDD Frequency Duplex Division
FFT Fast Fourier Transformation
FM Frequency Modulation
GPS Global Positioning System
GSM Global System for Mobile Communications
GUI Graphical User Interface
HMI Human Machine Interface
HSDPA High Speed Downlink Packet Access
HSPA High Speed Packet Access
ID Identifier
IEM In Ear Monitoring
IMD Intermodulation Distortion
ISM Industrial Scientific and Medical frequency band
LAN Local Area Network
LBT Listen before Talk
LTE Long Term Evolution
MMI Machine-to-Machine Interface
MRC Maximum Ratio diversity Combining
MSS Mobile Satellite Service
PAT Power Allocation Table
PMO Performance MOnitor
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PMSE Programme Making Special Events
PWMS Professional Wireless Microphone System
QoS Quality of Service
RAT Radio Access Technologies
REM Radio Environmental Map
RF Radio Frequency
RFID Radio Frequency Identifier
RMS Root Mean Square
ROI Return on Investment
RRM Radio Resource Manager
RRS Reconfigurable Radio System
RSS Received Signal Strength
RSSI Received Signal Strength Indication
sci scanning receiver interface
SCR Scanning Receiver
SINR Signal to Interference and Noise Ratio
SLA Service level Agreement
SLE Service Level Entry
SLM Service Level Monitor
SNR Signal to Noise Ratio
SRD Short Range Device
T-DAB Terrestrial Digital Audio Broadcast
TEDDI Terms and Definitions Interactive Database
TTI Transmission Time Interval
TTV Time To Violation
TVBD Television Band Device
UHF Ultra High Frequency
UMTS Universal Mobile Telecommunication System
UWB Ultra-Wideband
W-CDMA Wideband - Code Division Multiple Access
WiMax Worldwide Interoperability for Microwave access
WLAN Wireless Local Area Network
WSD White Space Device
4 Differences between mobile services and
Professional Audio Transmission
4.1 General remarks
This clause compares the differences in the operation of mobile services and PMSE systems and the features
implemented to meet those.
Mobile services technology is very advanced and has evolved dramatically over the last decade. Sophisticated
advancements have been widely implemented and have become state of the art. Therefore it has been suggested that the
PMSE market adopt features from the mobile world that have been widely accepted and proven as being very
beneficial.
This clause comments on the specifics of PMSE systems and those of mobile services. It also comments on why
features of mobile systems cannot be simply taken over one-to-one, and instead have to be adapted to the specifics of
PMSE.
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13 ETSI TR 102 799 V1.1.1 (2010-06)
4.2 Comparisons in the operation of PSME against other mobile
systems
PMSE systems are required to meet very high quality levels for audio transmission. This means e.g. audio bandwidths
of more than 20 kHz and SNRs of more than 80 dB. Consider e.g. a typical CD recording based on 16 bit resolution,
equal to 96 dB dynamic range. By contrast, for a simple voice telephone service 3 kHz audio bandwidth and SNRs in
the range of 20 dB are sufficient. However, the most critical criterion is that short interruptions are not acceptable on
PMSE, but can be tolerated on mobile systems. In moderate quality PMSE equipment, interruptions still have to be kept
below approximately 1 ms.
In general, PMSE systems so far are designed under the objective of maximizing audio quality and ensuring that the
quality levels are met 100 % of the time. In contrast to this, mobile systems are mainly designed under the objective of
maximizing capacity/spectral efficiency and coverage.
Increasing the coverage of a base station means the investments for installing a network are lowered, as a smaller
number of base stations are needed to cover a certain area.
Increasing the spectral efficiency of a system means that more traffic, either voice or data can be transferred in a given
swath of spectrum. As a consequence, the service provider can earn more money and increase the return on investment
(ROI) in spectrum licenses.
4.3 Latency
PSME systems require a maximum latency of 3 ms to 5 ms in order to maintain lip synchronisation. Unfortunately,
existing and planned mobile communication systems cannot support this latency requirement.
Various techniques which can be considered cognitive are used within various short range devices; these include Listen
Before Talk (LBT) and detect and avoid (DAA). Unfortunately these techniques allow a time gap before logging a new
frequency. PWMS require continuous transmission in order to convey the full range of speech or music. Therefore these
techniques are not suitable for PWMS usage.
4.4 Signalling between mobile and infrastructure equipment
PMSE devices are mainly unidirectional, whereas mobile phones are bidirectional. A wireless microphone on or behind
stage cannot be advised remotely by a central network element to change RF parameters such as e.g. its frequency or its
power during operation. Typically these parameters are fixed or can be configured by DIP-switches or menu settings by
using an infrared interface. Planning for those parameters is done in advance of an event production.
The same applies for the other direction e.g. an in-ear monitor on or behind the stage. The receiver worn by an artist or
actor typically cannot signal its actual receive quality to the in-ear-monitoring transmitter.
Back-channels are only partly implemented, mainly for battery supervision and power down of e.g. wireless
microphones.
Another aspect is that PMSE devices typically cannot be identified. A wireless microphone does not transmit its ID, nor
a training sequence or training symbols. Digitization would surely help here, but this comes at the cost of latency.
4.5 Link reliability
The main difference between PMSE and mobile service links is the link quality. For a high quality audio production, the
high link quality objective has to be met 100 % of the time. In a mobile system, link quality varies over time and
counteraction is taken on a sensed link quality degradation, so it is a reactive scheme. For PMSE a reactive scheme is
not sufficient, which means that if an upcoming link degradation is predicted or even known, a counteraction has to be
conducted in advance.
So far the need for ensuring a certain quality level 100 % of the time has led to the necessity to typically set PMSE
operational parameters in a way that the highest audio quality can still be met even under the worst case. It is clear that
this is a waste of radio resources; however the only way around this is that to know upcoming degradations well in
advance. Proactive schemes are needed in contrast to reactive schemes as implemented in mobile services.
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14 ETSI TR 102 799 V1.1.1 (2010-06)
Interruptions of service are intolerable for high quality classes of PMSE. There is a 100 % duty cycle for PMSE, so
there is no free time, no "quiet periods", which can be used to perform certain actions such as e.g. sensing by a PMSE
device.
From the viewpoint of reliability of PMSE, the high audio quality also has to be ensured in critical scenarios such as
objects being moved on the stage or the artist climbing between objects on stage, which is very common in theatre
production. Because PMSE today contains no link adaption, those scenarios are being taken care of through applying
enough fading margin in the link budget. A drop of a wireless link would lead to a stop of a production and therefore is
not accepted.
In summary, a minimum specified service level has to be met under all circumstances, for 100 % of the time. However
the required minimum service level may vary depending on whether a PMSE wireless device is used for a production
with artists or a conference system. Therefore the quality requirement is a scalable parameter depending on the
application.
4.6 Link quality
In figure 1, Comparison of reactive scheme of a mobile service and the newly proposed proactive scheme with C-PMSE
is given. In mobile systems (solid line in figure 1), link quality is continuously monitored and supervised.
Counteractions are triggered if the link quality falls below a certain quality threshold. In GSM, for example, a handover
due to interference may be initiated.
However, as stated in clause
...